Eleven minutes before the Boston bombs went off

Eleven minutes before the two explosions on April 15 at the Boston Marathon, surveillance video from a security camera at a nearby restaurant first picked up Dzhokhar and Tamerlan Tsarnaev, who became suspects in the attack. Tamerlan died as a result of injuries sustained in a subsequent confrontation with police. Dzhokhar, his younger brother, was charged Monday with use of a weapon of mass destruction and destruction of property resulting in death.

Eleven minutes before the two explosions on April 15 at the Boston Marathon, surveillance video from a security camera at a nearby restaurant first picked up Dzhokhar and Tamerlan Tsarnaev, who became suspects in the attack. Tamerlan died as a result of injuries sustained in a subsequent confrontation with police. Dzhokhar, his younger brother, was charged Monday with use of a weapon of mass destruction and destruction of property resulting in death.

Here is a breakdown of those 11 minutes, based on an affidavit filed with the criminal complaint. The times are approximations, compiled by the FBI from video and photographic evidence.

2:38 p.m. Two young men, both carrying large backpacks, turn onto Boylston Street from Gloucester Street and walk toward the Boston Marathon finish line. The first man, who the FBI believed was Tamerlan Tsarnaev, wore a dark baseball hat, sunglasses, a white shirt, dark coat and tan pants. The second man, believed to Dzhokhar Tsarnaev, wore a backward white baseball hat, a gray hoodie, light black jacket and dark pants. He walked behind his brother.

2:41 p.m. The surveillance camera, near the location of the second explosion, shows the two men standing together one half-block from the restaurant.

2:42 p.m. Tamerlan starts walking toward the finish line. He passes the front entrance of the restaurant on his way, backpack still on.

2:45 p.m. Dzhokhar starts walking toward the finish line, a cellphone in his left hand. Fifteen seconds later, he stops in front of the restaurant, facing the runners. He slips off the backpack, setting it at his feet and remains there for about four minutes. He occasionally looks at his cellphone and appears to take a photograph with it. At one point he appears to look at his phone, held at waist level, and “may be manipulating” it, according to the affidavit.

About 30 seconds before the first explosion, Dzhokhar put the phone to his ear for about 18 seconds.

2:49 p.m. A few seconds after he finishes the call, the people around him “can be seen reacting to the first explosion” in front of 671 Boylston St. Dzhokhar, as the crowd around him reacts in “in apparent bewilderment and alarm . . . appears calm.” He then started moving “calmly, but rapidly,” away from the finish line, without his backpack, according to the affidavit.

Ten seconds later, the second bomb explodes at 755 Boylston St., where Dzhokhar left the backpack.